1. Field of the Invention
The present invention relates broadly to rail fastening assemblies incorporating a generally S-shaped rail fastening clip for securing a railway rail to a cross tie or similar rail support or sleeper. The present invention relates, more particularly, to an improved two-piece rail fastening assembly of this character specifically adapted for holding railway rails, supported on conventional tie plates, to wooden cross ties.
2. Description of the Art
A railway rail is typically secured to a wooden cross tie by supporting the rail on a tie plate and affixing the tie plate to the cross tie by means of large spikes. There are usually four spike holes provided on each of the field and gage sides of the tie plate, two holes fairly close to the position the rail base flange assumes on the tie plate and two near the outer edge of the tie plate. The heads of the spikes driven through the holes adjacent the base flange of the rail overlap the edges of the rail flange to hold it.
Rail anchors secured to the rail beneath the flange, on either side of the cross tie, usually complement the foregoing arrangement to prevent longitudinal motion or creeping of the rail. It is also conventional to use other assemblies in combination with this fastening arrangement to retard or prevent overturn motion of the rails during use. With little variation, this has been the scheme routinely employed for years to secure a railway rail to a wooden tie.
For purposes relevant to the present invention, a different type of assembly is proposed in British Pat. No. 1,154,497. This patent discloses a rail fastening assembly making use of a generally s-shaped rail clip in combination with a specially constructed tie plate. The tie plate is secured to the cross tie by means of a pair of fixture bolts or screws at the outboard sides only. A rib runs laterally across the tie plate adjacent the position of the base flange of the rail when the same is in place, and is provided with a projection designed to grasp or otherwise engage the central leg of the S-shaped clip. The clip is twisted, by use of a special tool designed to apply a torsional force to it, and is then positioned on the tie plate in this twisted configuration. One leg of the S clip engaqes the base flange of the rail while the opposite free end rests on the tie plate. The rail is thus restrained by virtue of the torsional force existing in the S-shaped clip. There are obvious drawbacks to each of the systems described above. With respect to the first-mentioned system of spikes, rail anchors, and rail-overturn prevention devices, considerable track maintenance and attendant expense are involved. Application of all these device is costly. There is a tendency for the different parts to loosen and move away from the tie due to the dynamic conditions encountered during use and cyclic expansion and contraction as the result of varying weather conditions. When rails require replacement the spikes must be removed and after awhile, the ties become "spike killed" and they too must be replaced The expense involved in maintaining a track which employs this type of hold-down assembly is considerable--having been reported to be as high as $15,000.00 per year per mile of track. There are also substantial disadvantages with respect to the second-mentioned, S-clip fastening assembly. Tie plates must be specially designed to receive the S-shaped rail clip. Special tools are required to stress the clip properly and to install it in that stressed condition. Obviously, this system is not well-adapted for use on existing tracks because of its very construction.